Spacer or timing layer in color diffusion transfer film

ABSTRACT

Novel photographic products for use in color diffusion transfer, particularly color diffusion transfer systems for forming color images viewable without separation as reflection prints, which products include a neutralizing layer for lowering the environmental pH after application of an aqueous alkaline processing fluid and a &#39;&#39;&#39;&#39;timing&#39;&#39;&#39;&#39; spacer layer so disposed with respect to the neutralizing layer that the processing fluid must first diffuse through the spacer layer before contacting the neutralizing layer, the spacer layer comprising, as a continuous phase, the coalesced essence of an aqueous film-forming synthetic polymer dispersion which is substantially impermeable to the processing fluid and a discontinuous phase comprising a material which is permeable to the processing fluid.

United States Patent [191 Avtges et al.

[ Jan. 15, 1974 ABSTRACT Novel photographic products for use in color diffusion transfer, particularly color diffusion transfer systems for forming color images viewable without separation as reflection prints, which products include a neutralizing layer for lowering the environmental pH after application of an aqueous alkaline processing fluid and a timing spacer layer so disposed with respect to the neutralizing layer that the processing fluid must first diffuse through the spacer layer before contacting the neutralizing layer, the spacer layer comprising, as a continuous phase, the coalesced essence of an aqueous film-forming synthetic polymer dispersion which is substantially impermeable to the processing fluid and a discontinuous phase comprising a material which is 26 Claims, 1 Drawing Figure SPACER OR TIMING LAYER IN COLOR DIFFUSION TRANSFER FILM Primary ExaminerNorman G. Torchin [75] Inventors: James A. Avtges, Belmont; Jerome 33 Zf'ff* Schlnmg L. Reid, Natick; I-Ierbert N. Schlein, e Beverly; Lloyd D. Taylor, Lexington, all of Mass. [57] [73] Assignee: Polaroid Corporation, Cambridge,

Mass.

[22] Filed: Apr. 24, 1972 [21] Appl. No.: 246,779

[52] US. Cl 96/3, 96/29 D, 96/67, 96/77 [51] Int. Cl. G03c 7/00, G03c 5/54, G03c 1/76, G03c 1/48 [58] Field of Search 96/3, 29 D, 77

[56] References Cited UNITED STATES PATENTS permeable to the processing fluid. 3,625,685 l2/l97l Avtges et al. 96/29 D 3,415,645 l2/l968 Land 96/29 D SUPPORT |3- \CYAN DYE DEVELOPER LAYER N A\E%1ZF&'STXYEESILVER HALIDE |5-\ INTERLAYER |s LMAGENTA OYE DEVELOPER LAYER |7- .LEEEN-SENSITNE slLvER HALIDE EMULSION LAYER /j /INTERLAYER |9 L/YELLow DYE DEVELOPER LAYER /]rgu E s 5 s| 1g SILVER HAUDE 2| TJ-AUXILIARY LAYER zz-v /(-/IMAGE-RECEIVING LAYER 23- /-SPACER LAYER z4- j/NEuTRAL|zme LAYER 25- \l SUPPORT WW 15 m4 SUPPORT NCYAN DYE DEVELOPER LAYER RED-SENS|TIVE SILVER HALIDE EMULSION LAYER iNTERLAYER L MAGENTA DYE DEVELOPER LAYER SILVER HALI DE GREEN- NSI EMULS LA /-|NTERLAYER /YELLOW DYE DEVELOPER LAYER a'LfiE-sEuslTlvE SILVER HALIDE EMULSION LAYER -AUXILIARY LAYER l MAGE-RECEIVING LAYER /SPACER LAYER /*NEUTRALIZ|NG LAYER SUPPORT SPACER OR TIMING LAYER IN COLOR DIFFUSION TRANSFER FILM BACKGROUND OF THE INVENTION Various diffusion transfer systems for forming color images have heretofore been disclosed in the art. Generally speaking, such systems rely for color image formation upon a differential in mobility or solubility of a dye image-providing material obtained as a function of development so as to provide an imagewise distribution of such material which is more diffusible and which is therefore selectively transferred, at least in part, by diffusion, to a superposed dyeable stratum to impart thereto the desired color transfer image. The differential in mobility or solubility may for example be obtained by a chemical action such as a redox reaction or a coupling reaction.

The dye image-providing materials which may be employed in such processes generally may be characterized as either (l) initially soluble or diffusible in the processing composition but are selectively rendered non-diffusible in an imagewise pattern as a function of development; or (2) initially insoluble or non-diffusible in the processing composition but which are selectively rendered diffusible in an imagewise pattern as a function of development. These materials may be complete dyes or dye intermediates, e.g., color couplers.

As examples of initially soluble or diffusible materials and their application in color diffusion transfer, mention may be made of those disclosed, for example, in U. S. Pat. Nos. 2,647,049; 2,661 ,293; 2,698,244; 2,698,798; 2,802,735; 2,774,668; and 2,983,606. As examples of initially non-diffusible materials and their use in color transfer systems, mention may be made of the materials and systems disclosed in U. S. Pat. Nos. 3,443,939; 3,443,940; 3,227,550; 3,227,55l; 3,227,552; 3,227,554; 3,243,294 and 3,445,228.

In any of these systems, multicolor images are obtained by employing a film unit containing at least two selectively sensitized silver halide layers each having associated therewith a dye image-providing material exhibiting desired spectral absorption characteristics. The most commonly employed elements of this type are the socalled tripack structures employing a blue-, a greenand a red-sensitive silver halide layer having associated therewith, respectively, a yellow, a magenta and a cyan dye image-providing material.

A particularly usful system for forming color images by diffusion transfer is that described in U. S. Pat. No. 2,983,606, employing dye developers (dyes which are also silver halide developing agents) as the dye imageproviding materials. In such systems, a photosensitive element comprising at least one silver halide layer having a dye developer associated therewith (in the same or in an adjacent layer) is developed by applying an aqueous alkaline processing composition. Exposed and developable silver halide is developed by the dye developer which in turn becomes oxidized to provide an oxidation product which is appreciably less diffusible than the unreacted dye developer, thereby providing an imagewise distribution of diffusible dye developer in terms of unexposed areas of the silver halide layer, which imagewise distribution is then transferred, at least in part, by diffusion, to a dyeable stratum to impart thereto a positive dye transfer image. Multicolor images may be obtained with a photosensitive element having two or more selectively sensitized silver halide layers and associated dye developers, a tripack structure of the type described above and in various patents including the aforementioned U. S. Pat. No. 2,983,606 being especially suitable for accurate color recordation of the original subject matter.

In color diffusion transfer systems of the foregoing description, color images are obtained by exposing a photosensitive element or negative component comprising at least a light-sensitive layer, e.g., a gelatino silver halide emulsion layer, having a dye imageproviding material associated therewith in the same or in an adjacent layer, to form a developable image; developing this exposed element with a processing composition to form an imagewise distribution of a soluble and diffusible image-providing material; and transferring this imagewise distribution, at least in part, by diffusion, to a superposed receiving element or positive component comprising at least a dyeable stratum to impart to this stratum a color transfer image. The negative and positive components may be separate elements which are brought together during processing and thereafter either retained together as the final print or separated following image formation; or they may together comprise a unitary structure, e.g., integral negative-positive film units wherein the negative and positive components are laminated and/or otherwise physically retained together at least prior to image formation.

While the present invention is applicable both to those systems wherein the dyeable stratum is contained on a separate element and to those systems wherein the dyeable stratum and the photosensitive strata comprise a unitary structure, of particular interest are those integral negative-positive film units adapted for forming color transfer images viewable without separation, i.e., wherein the positive component need not be separated from the negative component for viewing purposes. Generally, such film units comprise a plurality of essential layers including a negative component comprising at least one light-sensitive silver halide and associated dye image-providing material and a positive component comprising dyeable stratum. These components may be laminated together or otherwise secured together in physical juxtaposition as a single structure. Film units intended to provide multicolor images comprise two or more selectively sensitized silver halide layers each having associated therewith an appropriate dye image-providing material exhibiting desired spectral absorption characteristics. As was heretofore mentioned the most commonly employed negative components for forming multicolor images are of the tripack structure containing a blue-, a greenand a redsensitive silver halide layer having associated therewith in the same or in a contiguous layer a yellow, a magenta and a cyan dye image-providing material respectively. lnterlayers or spacer layers may if desired be provided between the respective silver halide layers and associated dye image-providing materials. In addition to the aforementioned essential layers, such film units further include means for providing a reflecting layer between the dyeable stratum and the negative component in order to mask effectively the silver image or images formed as a function of development of the silver halide layer or layers and any remaining associated dye image-providing material and to provide a background for viewing the color image formed in the dyeable stratum, without separation, by reflected light. This reflecting layer may comprise a preformed layer of a reflecting agent included in the essential layers of the film unit or the reflecting agent may be provided after photoexposure, e.g., by including the reflecting agent in the processing composition. These essential layers are preferably contained on a transparent dimensionally stable layer or support member positioned closest to the dyeable stratum so that the resulting transfer image is viewable through this transparent layer. Most preferably another dimensionally stable layer which may be transparent or opaque is positioned on the opposed surface of the essential layers so that the aforementioned essential layers are sandwiched or confined between a pair of dimensionally stable layers or support members, at least one of which is transparent to permit viewing therethrough of a color transfer image obtained as a function of development of the exposed film unit in accordance with the known color diffusion transfer system such as will be detailed hereinafter. In a particularly preferred form such film units are employed in conjunction with a rupturable container of known description containing the requisite processing composition and adapted upon application of pressure of applying its contents to develop the exposed film unit, e.g., by applying the processing composition in a substantially uniform layer between the dyeable stratum and the negative component. lt will be appreciated that the film unit may optionally contain other layers performing specific desired functions, e.g., spacer layers, etc.

Opacifying means may be provided on either side of the negative component so that the film unit may be processed in the light to provide the desired color transfer image. In a particularly useful embodiment such opacifying means comprise an opaque dimensionally stable layer or support member positioned on the free or outer surface of the negative component, i.e., on the surface of the film unit opposed from the positive component containing the dyeable stratum to prevent photoexposure by actinic light incident thereon from this side of the film unit and an opacifying agent applied during development between the dyeable stratum and the negative component, e.g., by including the opacifying agent in a developing composition so applied, in order to prevent further exposure (fogging) by actinic light incident thereon from the other side of the film unit when the thus exposed film unit is developed in the light. The last-mentioned opacifying agent may comprise the aforementioned reflecting agent which masks the negative component and provides the requisite background for viewing the transfer image formed thereover. Where this reflecting agent does not by itself provide the requisite opacity it may be employed in combination with an additional opacifying agent in order to prevent further exposure of the light-sensitive silver halide layer or layers by actinic light incident thereon.

As examples of such integral negative-positive film units for preparing color transfer images viewable without separation as reflection prints, mention may be made of those described and claimed in U. S. Pat. Nos.

3,415,644; 3,415,645; 3,415,646; 3,473,925; 3,573,043; 3,576,625; 3,573,042; 3,594,164; and 3,594,165.

In general, the integral negative-positive film units of the foregoing description, e.g., those described in the aforementioned patents, are exposed to form a developable image and thereafter developed by applying the appropriate processing composition to develop exposed silver halide and to form, as a function of development, an imagewise distribution of diffusible dye image-providing material which is transferred, at least in part by diffusion, to the dyeable stratum to impart thereto the desired color transfer image, e.g., a positive color transfer image. Common to all of these systems is the provision of a reflecting layer between the dyeable stratum and the photosensitive strata to mask effectively the latter and to provide a background for viewing the color image contained in the dyeable stratum, whereby this image is viewable without separation, from the other layers or elements of the film unit. In certain of these systems, this reflecting layer is provided prior to photoexposure, e.g., as a preformed laycr included in the essential layers of the laminar structure comprising the film unit, and in others it is provided at some time thereafter, e.g., by including a suitable lightreflecting agent, for example, a white pigment such as titanium dioxide, in the processing composition which is applied between the dyeable stratum and the next adjacent layer to develop the latent image and to form the color transfer image.

The dye image-providing materials which may be employed in such processes generally are selected from those materials heretofore mentioned and disclosed in the illustrative patents which were initially soluble or diffusible in the processing composition but which are selectively rendered non-diffusible as a function of development or those which are initially insoluble or nondiffusible in the processing composition but are selectively rendered diffusible as a function of development. These materials may be complete dyes or dye intermediates, e.g., color couplers.

A preferred opacification system to be contained in the processing composition is that described in the copending applications of Edwin H. Land, Ser. No. 43,782, filed June 5, 1970 and now abandoned, and Ser. No. 101,968, filed Dec. 28, 1970 and now U.S. Pat. No. 3,647,437, comprising an inorganic reflecting pigment dispersion containing at least one optical filter agent at a pH above the pKa of the optical filter agent in a concentration effective, when the procesing composition is applied, to provide a layer exhibiting optical transmission density than about 6.0 density units with respect to incident radiation actinic to the photosensitive silver halide layer and optical reflection density than about 1.0 density with respect to incident visible radiation.

In lieu of having the reflecting pigment contained in the processing composition, e.g., as disclosed in the aforementioned copending applications, the reflecting pigment needed to mask the photosensitive strata and to provide the requisite background for viewing the color transfer image formed in the receiving layer may be contained initially in whole or in part as a preformed layer in the film unit. As an example of such a preformed layer, mention may be made of that disclosed on the copending applications of Edwin H. Land, Ser. Nos. 846,441, filed July 31, 1969, now U.S. Pat. No. 3,615,421, and 3,645, filed Jan. 19, 1970 and now U.S. Pat. No. 3,620,724. The reflecting pigment may be generated in situ as is disclosed in the copending applications of Edwin H. Land, Ser. Nos. 43,741 and 43,742, both filed June 5, 1970 and now U. S. Pat. Nos. 3,647,434 and 3,647,435, respectively.

In the various color diffusion transfer systems which have previously been described and which employ an aqueous alkaline processing fluid, it is well known to employ an acid-containing layer to lower the environmental pH following substantial dye transfer in order to increase the image stability and/or to adjust the pH from a first pH at which the imaging dyes are diffusible to a second (lower) pH at which they are not. For example, U. S. Pat. No. 3,362,819 discloses systems wherein the desired pH reduction may be effected by providing a polymeric acid layer adjacent the dyeable stratum. These polymeric acids may be polymers which contain acid groups, e.g., carboxylic acid and sulfonic acid groups, which are capable of forming salts with alkali metals or with organic bases; or potentially acidyielding groups such as anhydrides or lactones. Preferably the acid polymer contains free carboxyl groups. As examples of other useful neutralizing layers, in addition to those disclosed in the aforementioned U. S. Pat. No. 3,362,819, mention may be made of those disclosed in the following copending applications: Ser. No. 165,171 of Schlein et al., filed July 22, 1971; Ser. No. 214,746 of Bedell, filed Jan. 3, 1972; Ser. No. 208,616 of Taylor, filed Dec. 16, 1971; Ser. No. 231,835 of Sahatjian et al., filed Mar. 6, 1972, etc.

An inert interlayer or spacer layer may be and is preferably disposed between the polymeric acid layer and the dyeable stratum in order to control the pH reduction so that it is not premature and hence interferes with the development process, e.g., to time control the pH reduction. Suitable spacer or timer layers for this purpose are described with particularity in U.S. Pat. No. 3,362,819 and in others, including U.S. Pat. Nos, 3,419,389; 3,421,893; 3,433,633; 3,455,686; and 3,575,701.

While the acid layer and associated spacer layer are preferably contained in the receiving element employed in systems wherein the dyeable stratum and photosensitive strata are contained on separate elements, e.g., between the support for the receiving element and the dyeable stratum; or associated with the dyeable stratum in those integral film units, e.g., on the side of the dyeable stratum opposed from the negative component, they may, if desired, be associated with the photosensitive strata, as is disclosed, for example, in U.S. Pat. Nos. 3,362,821 and 3,573,043. In film units such as those described in the aforementioned U. S. Pat. Nos. 3,594,164 and 3,594,165, they also may be contained on the spreader sheet employed to facilitate application of the processing fluid.

The present invention is directed to another type of spacer layer to be employed in association with a neutralizing layer for lowering the environmental pH in color diffusion transfer systems of the type previously described, which spacer layer provides the distinct advantages and beneficial results which will be described hereinafter in the detailed description of the invention.

BRIEF DESCRIPTION OF DRAWING The FIGURE is an enlarged, fragmentary, diagrammatic, sectional view of a film unit contemplated by this invention.

SUMMARY OF THE INVENTION In accordance with the present invention, the spacer layer comprises, as a continuous phase, the coalesced essence of an aqueous film-forming synthetic polymer dispersion which is substantially impermeable to the aqueous alkaline processing fluid and a discontinuous phase comprising a material which is permeable to the processing fluid.

DESCRIPTION OF PREFERRED EMBODIMENT The preferred photographic products contemplated by this invention are of the so-called integral negativepositive tripack configuration, the neutralizing and spacer layers being contained in the positive component of the film unit.

As was heretofore mentioned, in diffusion transfer systems for preparing color images, e.g., those systems previously described, wherein the exposed photosensitive element is developed by applying an aqueous alkaline processing fluid, it is well known to employ a neutralizing layer to lower the environmental pH following substantial dye transfer. A spacer or timing layer may be disposed between the neutralizing layer and the layer or layers where or between which the processing fluid is applied to initiate development so that the processing fluid must first diffuse through this spacer layer before contacting the neutralizing layer to effect the desired pH reduction. The purpose of this spacer layer is to control the pH reduction so that it is not premature and hence interfere with the development process, e.g., to time control the pH reduction by delaying contact with the neutralizing layer. Various neutralizing and spacer layers of this description have heretofore been disclosed.

The neutralizing layer may comprise an acidcontaining compound, e.g., a polymeric acid, containing acid groups, or potentially acid-yielding groups, which are capable of forming salts with alkali metals or with organic bases. It may also comprise a polymeric salt of a monomeric strong acid and a polymeric weak base which form polymeric bases upon neutralization by contact with the alkaline processing fluid, as is described in the aforementioned Taylor application, Ser. No. 208,616, filed Dec. 16, 1971.

The timing or spacer layers heretofore disclosed may in general be referred to as those whose permeability is inversely temperature dependent, i.e., whose permeability to solubilized alkali derived ions decreases under conditions of increasing temperature; and those which have a normal temperature dependence, i.e., are more permeable at higher temperatures. The particular spacer layer employed may fall within an area on a permeation-time vs. temperature graph wherein the average slope of the line varies from slightly positive to slightly negative. A slope of zero would indicate that, at the ordinary processing range of approximately 40F to 100F the pH lowering mechanism would operate irrespective of the temperature. It must be emphasized that the precise temperature-permeation characteristics of the spacer layer must be tailored to the photographic system selected as a whole and are dependent upon the relative dye diffusion constants and development times of the selected system which are required at various temperatures. In this respect determious film-forming synthetic polymer dispersion which is substantially impermeable to the processing fluid and a discontinuous phase comprising a material which is permeable to the processing fluid so as to permit diffusion of solubilized alkali derived ions through the layer to the neutralizing layer.

Preferred latices which may be employed as the continuous phase of the timing layers of this invention include a 60-38-2 copolymer of methylmethacrylate, butylacrylate and acrylic acid, respectively; a 60-30-4-6 copolymer of butylacrylate, diacetone acrylamide, styrene and methacrylic acid, respectively; and a 60-30-4-6-1.5-0.5 copolymer of butylacrylate, diacetone acrylamide, styrene, methacrylic acid, 2- sulfoethyl methacrylate and divinyl benzene, respectively, all proportion designations being on a dry weight basis. Among other useful latices, mention may be made of polyvinyl chloride, vinyl chloride-vinyl acetate copolymers, acrylic polymers and copolymers as, for example, a terpolymer of butylacrylate, methylmethacrylate and small amounts of acrylic acid or methacrylic acid, and innumerable other latices which will readily come to mind to one of ordinary skill in polymer chemistry. An extensive compilation of appropriate latices which may be utilized herein will be found in U. S. Pat. No. 2,795,564.

Among the various permeable materials which may be employed as the discontinuous phase (hereinafter referred to simply as the permeator"), mention may be made of isopropyl cellulose, preferably containing about 1.3 isopropyl groups per cellulosic monomer unit, hydroxypropyl cellulose, acrylonitrile acrylic acid copolymers, methylacrylate acrylic acid copolymers, preferably containing about 3 percent by weight acrylic acid, poly-N-ethyl acrylamide, polyacrylamide, polyethylene oxide, terpolymers of N-ethylacrylamide, methylacrylamide and acrylamide, copolymers of N- ethylacrylamide and 2-vinyl pyridine, copolymers of N-isopropyl acrylamide and N-vinyl pyrrolidone, copolymers of N-isopropyl acrylamide and dimethylaminoethyl acrylate, etc. Other useful permeators include graft copolymers of the type disclosed in the aforementioned U. S. Pat. No. 3,575,701 and which are disclosed in this patent as providing useful timing layers.

As heretofore mentioned, the coalesced latex portion is denoted as the continuous phase, while the permeator component is denoted as the discontinuous phase. Such terminology connotes an admixture of the two components with the former component being present in greater concentration than the latter which may, if desired, be present in the form of continuous channels, etc., throughout the coalesced latex. The ratio of latex to permeator employed may vary in accordance with the particular rate or degree of diffusibility desired in the photographic system in which it is employed. It will be appreciated that as the concentra tion of permeator increases, the permeability of the layer also increases. A typical latex/permeator timing layer of this invention may contain a ratio of latex to permeator on the order of from about 19:1 to about 99:1, a typical ratio being on the order of about 40:1. However, the selection of the particular ratios of ingredients to be employed in a given film unit will be readily apparent to those skilled in the art and the ratios given above are accordingly by way of illustration only.

Generally speaking, the timing layers of this invention possess a total thickness such that, if the layer consisted only of the coalesced latex, it would be impermeable to the alkaline processing fluid. It may, for example, be on the order of 0.1 to 0.7 mil thick and may, for example, contain on the order of 300-1 ,700 mgs. of solids/sq. ft. of surface area. Where employed in systems wherein the photosensitive strata are to be exposed and/or the resulting image is to be viewed through this layer, it is desirable that the layer, like any other layers through which exposure is to be made and/or the image viewed, should be as thin as possible. In such instances, it will also be appreciated that the timing layer of this invention should also be as clear or transparent to visible light as possible. To achieve such clarity, it is important that the latex and permeator be compatible, since incompatibility will result in a film which may not be as transparent or clear as desired and is not macroscopically homogeneous. With various latex/permeator mixtures, it will be appreciated that various degrees of compatibility may be achieved. The indicativeness of such compatibility may be appreciated by the clarity of the ultimate film produced light scatter being a concomitant result of the absence of compatibility between the latex and the permeator used therewith, and being further indicative of the degree of macromolecular non-homogeneity. It will therefore be recognized that the discontinuities provided within the coalesced latex film by the permeator must, in such instances, be sufficiently small so as to obviate the induction of scattering of light incident thereon. The layer may be considered to be homogeneous if the coalesced latex contains a permeator which is distributed compatibly throughout the coalesced latex film so as not to produce scattering of incident light. In absolute terms, that is, on the microscopic level, the layer will generally consist essentially of the coalesced latex with a multiplicity of small localized areas comprising the permeator.

From the foregoing discussion, it will be appreciated the permeability of the timing layer is obtained from the permeator component, the latex component being substantially impermeable. The selection of the particular permeator employed will therefore be extremely important, if not critical, to achieve the desired time control of neutralization. In some systems it may be desired to employ permeators having temperature inversely dependent characteristics, as previously discussed; whereas in other systems it may be desired to employ those having normal temperature dependence, e.g., which are not temperature inversely dependent, in order to achieve greater temperature latitude, i.e., images of comparable quality over a wider temperature range. In the illustrative film unit to be detailed hereinafter, polyacrylamide, a permeator having normal temperature dependence, was selected to achieve maximum image quality over a wide temperature range from hot to cold. Accordingly, an important feature of the present invention is the ability to obtain a wide degree of flexibility in terms of temperature latitude by permitting one skilled in the art to select from a wide list of available permeators those with varying temperature dependent permeabilities and thereby select the one which is most suitable for his particular system. The permeator so selected may possess normal temperature dependence or inverse temperature dependence in varying degrees and such selection will be apparent to one skilled in the art in the light of the present disclosure.

Apart from the selection of the particular permeator and the ratio of latex to permeator, the permeability of the layer is also in part dependent upon the latex particle size. The greater the particle size the greater the permeator-filled interstices and in turn the more permeable the layer. Conversely, the smaller the particle size, the smaller the interstices and in turn the tighter or less permeable the layer. In a typical timing layer contemplated by this invention, the latex particle size may be in the order of from about 0.095;). to about 0.l30p..

While the latex and permeator constitute the essential ingredients of the timing layers of this invention, they may also include other ingredients, e.g., stabilizers, ultraviolet light absorbers and hardeners such as succindialdehyde, performing specific desired functions. Succindialdehyde, for example, has been found to provide an additional mechanism for tailoring the permeation characteristics of various coalesced latex interlayers by forming a crosslinked system with certain of the permeation-inducing components as, for example, polyacrylamide. In addition, various surfactants, coating aids, etc., may be incorporated in the latices utilized herein to modulate the coalescense required, etc., to the system. In addition, control of ion concentration and adjustment of other parameters. may be routinely carried out according to the desires of the operator. Such materials and techniques are well within the ambit of knowledge possessed by one of ordinary skill in latex chemistry.

Latex/permeator layers of the foregoing description for use as interlayers in the negative component of the film unit, i.e., as interlayer or spacer layers between one or more of the silver halide layers and associated dye image-providing material and another such silver halide layer and associated dye image-providing material have been described and claimed in our U. S. Pat. No. 3,625,685. However, it has never heretofore been suggested that they be employed as timing layers associated with a neutralizing layer as herein contemplated. Latices of the above-mentioned particle size range for use in such negative interlayers is described and claimed in the copending application of Charles I. Sullivan, Ser. No. 209,229, filed Dec. 17, 1971.

As was heretofore mentioned, the present invention is useful in systems wherein the photosensitive strata and the dyeable stratum are contained on separate elements; and in systems wherein they are contained together as a unitary film unit, e.g., in the integral negative-positive film units previously described. In the former type, the neutralizing system, i.e., neutralizing and timing layers, is contained in association with the dyeable stratum, e.g., in an image-receiving element comprising a support carrying the neutralizing layer, the timing layer and the dyeable stratum. In like manner, in the integral negative-positive film units, the neutralizing layer and associated timing layer are associated with the dyeable stratum, e.g., on the side of the dyeable stratum opposed from the negative component, with the timing layer disposed between the dyeable stratum and the neutralizing layer; provided that in those integral negative-positive film units wherein the processing fluid is applied between the surface of the film unit and a superposed spreader sheet or separate sheet-like element employed to facilitate application of the processing fluid, the neutralizing system may, if desired, be contained on this separate sheet-like element.

Of particular interest are those film units such as the heretofore described integral negative-positive film units wherein the negative and positive components are at least retained together after image formation as the final print. The invention will accordingly be illustrated by reference to a typical film unit of this description.

As shown in the drawing, such a film unit may comprise, as the essential layers, a layer 13 of cyan dye developer, red-sensitive silver halide emulsion layer 14, interlayer 15, a layer of magenta dye developer 16, green-sensitive silver halide emulsion layer 17, interlayer 18, yellow dye developer layer l9, blue-sensitive silver halide emulsion layer 20, auxiliary layer 21, image-receiving layer or dyeable stratum 22, spacer layer 23, and a pH-reducing or neutralizing layer 24. Layers 13-21 comprise the negative component and layers 22-24 comprise the positive component. These essential layers are shown to be confined between a dimensionally stable layer or support member 12 which is preferably opaque so as to permit development in the light and dimensionally stable layer or support member 25 which is effectively transparent to permit viewing of a color transfer image formed as a function of development in receiving layer or dyeable stratum 22.

Layers l2 and 25 are preferably dimensionally stable liquid-impermeable layers which when taken together may possess a processing composition solvent vapor permeability sufficient to effect, subsequent to substantial transfer image formation and prior to any substantial environmental image degradation to which the resulting image may be prone, osmotic transpiration of processing composition solvent in a quantity effective to decrease the solvent from a first concentration at which the color-providing material is diffusible to a second concentration at which it is not. Although these layers may possess a vapor transmission rate of l or less gms./24 hrs./l00 in. /mil., they preferably possess a vapor transmission rate for the processing composition solvent averaging not less than about gms./24 hrs/100 in. /mil., most preferably in terms of the preferred solvent, water, a vapor transmission rate averaging in excess of about 300 gms. of water/24 hrs/100 in. /mil., and may advantageously comprise a microporous polymeric film possessing a pore distribution which does not unduly interfere with the dimensional stability of thelayers or, where required, the optical characteristics of such layers. As examples of useful materials of this nature, mention may be made of those having the aforementioned characteristics and which are derived from ethylene glycol terephthalic acid; vinyl chloride polymers; polyvinyl acetate; cellulose derivatives, etc. As heretofore noted layer 12 is of sufficient opacity to prevent fogging from occurring by light passing therethrough, and layer 26 is transparent to permit photoexposure and for viewing of a transfer image formed on receiving layer 23.

The silver halide layers preferably comprise photosensitive silver halide, e.g., silver chloride, bromide or iodide or mixed silver halides such as silver iodobromide or chloriodobromide dispersed in a suitable colloidal binder such as gelatin and such layers may typically be on the order of 0.6 to 6 microns in thickness. It will be appreciated that the silver halide layers may and in fact generally do contain other adjuncts, e.g.,

chemical sensitizers such as are disclosed in U. S. Pat. Nos. 1,574,944; 1,623,499; 2,410,698; 2,597,856; 2,597,915, 2,487,850, 2,518,698; 2,521,926; etc.; as well as other additives performing specific desired functions, e.g., coating aids, hardeners, viscosityincreasing agents, stabilizers, preservatives, ultraviolet absorbers and/or speed-increasing compounds. While the preferred binder for the silver halide is gelatin, others such as albumin, casein, zein, resins such as cellulose derivatives, polyacrylamides, vinyl polymers, etc., may replace the gelatin in whole or in part.

The respective dye developers, which may be any of those heretofore known in the art and disclosed for example in U. S. Pat. No. 2,983,606, etc., are preferably dispersed in an aqueous alkaline permeable polymeric binder, e.g., gelatin as a layer from about 1 to 7 microns in thickness.

lnterlayers 15, 18 and 21 may comprise an alkaline permeable polymeric material such as gelatin and may be on the order of from about 1 to microns in thickness. As examples of other materials for forming these interlayers, mention may be made of those disclosed in U. S. Pat. Nos. 3,421,892, 3,575,701, 3,615,422 and 3,625,685. These interlayers may also contain additional reagents performing specific functions and the various ingredients necessary for development may also be contained initially in such layers in lieu of being present initially in the processing composition, in which event the desired developing composition is obtained by contacting such layers with the solvent for forming the processing composition, which solvent may include the other necessary ingredients dissolved therein.

The image-receiving layer may be on the order of 0.25 to 0.4 mil. in thickness. Typical materials heretofore employed for this layer include dyeable polymers such as nylon, e.g., N-methoxymethyl polyhexamethylene adipamide; partially hydrolyzed polyvinyl acetate; polyvinyl alcohol with or without placticizers; cellulose acetate with filler as, for example, onehalf cellulose acetate and one-half oleic acid; gelatin; polyvinyl alcohol or gelatin containing a dye mordant such as poly-4-vinylpyridine, etc. Such receiving layers may, if desired, contain suitable mordants, e.g., any of the conventional mordant materials for acid dyes such as those disclosed, for example, in the aforementioned U. S. Pat. No. 3,227,550; as well as other additives such as ultraviolet absorbers, pH-reducing substances, etc. It may also contain specific reagents performing desired functions, e.g., a development restrainer, as disclosed, for example, in U. S. Pat. No. 3,265,498.

The spacer or timing layer may be on the order of 0.1 to 0.7 mil. thick. In accordance with the present invention, it will comprise a latex/permeator layer as heretofore described.

The neutralizing layer may be on the order of 0.3 to 1.5 mil. in thickness. In accordance with this invention, it may comprise any of the neutralizing layers heretofore disclosed for this purpose, e.g., those disclosed in the aforementioned patents and copending applications. It may contain as much as 3,000 mgs./ft. of solids although the coverage is preferably appreciably less.

As was heretofore mentioned, it may in some instances be desirable to employ a latex of a predetermined particle size. As was disclosed in the aforementioned copending application Ser. No. 209,229, the particle size ofthe latex may be controlled within a predetermined desired particle size during its manufacture simply by regulating the amount of emulsifier employed in the synthesis of the latex. The greater the amount of emulsifier employed, the finer the particle size; and, conversely, with lesser amounts, coarser par ticles are obtained. In the following illustrative syntheses, latex particles within the heretofore mentioned range of 0095p. to 0115p. were obtained by employing 0.5 t 0.2 of emulsifier to 100 parts of monomer mix.

Preparation of a -30-4-6 Copolymer of Butylacrylate, Diacetone Acrylamide, Styrene and Methacrylic Acid.

To a reactor containing 1,700 g. of deionized water add 11.52 g. of a 45 percent solution ofDowfax 2A1 (trademark of Dow Chemical Co. for an emulsifier, sodium dodecyl diphenylether disulfonate). Adjust the temperature of the reactor to about C. In a separate container add 621.6 g. of butylacrylate, 38.52 g. of styrene and 64.35 g. of methacrylic acid while agitating. Then add 310.8 g. of diacetone acrylamide. When the diacetone acrylamide is almost dissolved (approximately 15 minutes), add 16.77 g. of deionized water while continuing mixing. Add about 15 percent (158.0 g.) of this mixture to the reactor slowly while using moderate agitation and while maintaining the temperature at about 75C. Mix for about 10 minutes and then add about 44.26 g. of an initiator solution prepared by dissolving 4.1 1 g. of potassium persulfate in 130.0 g. of deionized water. When the reaction has peaked, add the remaining percent of the monomer mix at about 9.9 g./min. while maintaining the temperature between about 7883C. About 30 minutes after beginning the addition of the rest of the monomer, start adding 88.51 g. of the above-mentioned initiator and continue at a rate of about 0.98 g./min. About 30 minutes after completing. this step, add a solution of 0.40 g. of tertiary butyl hydroperoxide and 0.22 g. of 45 percent Dowfax 2A1 in 2.24 g. of deionized water and mix well. Then add a solution of 0.40 g. of ascorbic acid in 43.4 g. of deionized water while mixing well. Hold the temperature of the mixture at about 788 3C for about 2 hours more to provide an emulsion of the above-mentioned copolymcr of butylacrylate, diacetone acrylamide, styrene and methacrylic acid.

While the latex prepared above may be employed in the preparation of the interlayer coating solutions to which this invention is directed, it is preferred that the pH first be adjusted from the initial acidic pH which may be on the order of about 2.2 to a more neutral pH, e.g., a pH on the order of from about 6.0 to about 8.5. While there does not appear to be any sensitometric advantages in this neutralizing step and the latex may therefore be employed as prepared above and without being neutralized, it has been found that neutralizing enhances the stability of the latex polymer during the handling and coating operations. For example, the neutralized latex has a much higher shear and can stand more abuse with the pumps and other equipment employed in the handling and coating steps.

This neutralization may be obtained by adding a suitable base, e.g., an ammonium hydroxide solution, to the emulsion prepared above. If desired, bases having a quantitatively traceable cation may be employed as a tagging means for quantitative analysis of the layer. As an example of such a base, mention may be made of rubidium hydroxide, cesium hydroxide and the like.

The coating solution for preparing the timing layer may be obtained simply by adding an aqueous solution of the desired permeator, e.g. polyaerylamide, to the the following:

latex emulsion as prepared above to provide the latex/permeator aqueous coating mixture containing the appropriate ratios ofingredients. [It will be appreciated that any additional desired reagents may also be so included] This mixture may then be coated to provide the timing layer at the desired coverage by known coating techniques.

By way of further illustrating the practice of this invention and the types of film units to which it is directed, an integral negative-positive film unit of the type described and claimed in U. S. Pat. No. 3,415,644 and shown in the illustrative drawing may be prepared, for example, by coating, in succession, on a gelatin subbed, 4 mil. opaque polyethylene terephthalate film base, the following layers:

1. a layer of cyan dye developer dispersed in gelatin and coated at a coverage of about 100 mgs./ft. of dye and about 80 mgs./ft. of gelatin;

2. a red-sensitive gelatino silver iodobromide emulstion coated at a coverage of about 140 mgs./ft. of silver and about 70 mgs./ft. of gelatin;

3. a layer of a 60-30-4-6 copolymer of butylacrylate, diacetone acrylamide, styrene and methacrylic acid and polyacrylamide coated at a coverage of about lSO mgs./ft. of the copolymer and about mgs./ft. of polyacrylamide;

4. a layer of magenta dye developer dispersed in gelatin and coated at a coverage of about 100 mgs./ft. of dye and about 100 mgs./ft. of gelatin;

5. a green-sensitive gelatino silver iodobromide emulsion coated at a coverage of about 100 mgsz/ft. of silver and about 50 mgs./ft. of gelatin;

6. a layer containing the copolymer referred to above in layer 3 and polyacrylamide coated at a coverage of about 100 mgs./ft. of copolymer and about .12 mgs./ft. of polyacrylamide;

7. a layer of yellow dye developer dispersed in gelatin and coated at a coverage of about 70 mgs./ft. of dye and about 56 mgs./ft. of gelatin;

8. a blue-sensitive gelatino silver iodobromide emulsion layer including the auxiliary developer 4'- methylphenyl hydroquinone coated at a coverage of about 120 mgs./ft. of silver, about 60 mgs./ft. of gelatin and about 30 mgs./ft. of auxiliary developer; and

9. a layer of gelatin coated at a coverage of about 50 mgs./ft. of gelatin.

The three dye developers employed above may be CHa 14 a cyan dye developer;

HO-CI-Ir-CIQ Q N sor- ?-N=N cm HO-CH:C z 0 0 N r-HgO O (|)H ilCHzCI-Ig A magenta dye developer; and

O CaH7 1 1'-Hz0 O O (|)H O-CHz-CH:

a yellow d ye developer.

Then a transparent 4 mil. polyethylene terephthalate film base may be coated, in succession, with the following illustrative layers:

1. the partial butyl ester of polyethylene/maleic anhydride copolymer prepared by refluxing, for l4 hours, 300 grams of high viscosity poly-(ethylene/maleic anhydride), 140 grams of n-butyl alcohol and 1 cc. of percent phosphoric acid to provide a polymeric acid layer at a coverage of about 2,500 mgs./ft.

2. a timing layer containing about a 40:1 ratio of a 60-30-4-6 copolymer of butylacrylate, diacetone acrylamide, styrene and methacrylic acid and polyacrylamide at a coverage of about 500 mgs./ft. and

3. a 2:1 mixture, by weight, of polyvinyl alcohol and poly-4-vinylpyridine, at a coverage of about 400 mgs./ft. and including about 20 mgs./ft. of a development restrainer, l-phenyl-5-mercaptotetrazole, to provide a polymeric image-receiving layer containing development restrainer.

The two components may then be laminated together to provide the desired integral film unit.

A rupturable container comprising an outer layer of lead foil and an inner liner or layer of polyvinyl chloride retaining an aqueous alkaline processing solution may then be fixedly mounted on the leading edge of each of the laminates, by pressure-sensitive tapes, interconnecting the respective container and laminates so that, upon application of compressive pressure to the container to rupture the containers marginal seal, its contents may be distributed between the dyeable stratum (layer 3 of the positive component) and the gelatin layer (layer 9) of the negative component.

An illustrative processing composition to be employed in the rupturable container may comprise the following properties of ingredients:

Water I00 cc. Potassium hydroxide ll.2 gms. Hydroxyethyl cellulose (high viscosity) [commercially available from Hercules Powder Co. Wilmington, Delaware, under the trade name Natrasol 250] 3.4 gms. N-phenethyLa-picolinium bromide 2.7 gms. Benzotriazole l.l5gms. Titanium dioxide 50.0 gms.

( 2.08 gms.

H L H NW \WN n-C H -o I2 15 O 0. 52 gms.

OH OH ami-n /O \l O 1.18 gms.

O OH H (II-CH: CH2NC1zlizs-' C-CH: H

This film unit may then be exposed in known manner to form a developable image and the thus exposed element may then be developed by applying compressive pressure to the rupturable container in order to distribute the aqueous alkaline processing composition, 65

thereby forming a multicolor transfer image which is viewable through the transparent polyethylene terephthalate film base as a positive reflection print.

The timing layers of this invention afford certain distinct advantages to the practitioner. To fully appreciate these advantages, one must take note of the fact that, from the standpoint of commercial production, each layer of the contemplated film unit must be readily synthesized, the ingredients of the layer should be adaptable for adjustment or modification in accordance with the particular film unit employed and its sensitometric design, and the layer should be easily appliable, e.g., readily coatable. In addition, any layers through which exposure is to be made and/or the image is to be viewed should be as thin and transparent as possible.

The novel timing layers of this invention are readily obtainable from aqueous coating media, thereby avoiding the obvious disadvantages inherent in the use of materials which must be coated from organic solvents. Chief of the advantages obtained in the use of aqueous media in lieu of organic solutions are the elimination of the need for organic solvents which are typically volatile, their storage before use, special equipment needed for coating and solvent recovery or recycling, the inherent danger in the use of volatile solvents, as well as possible contamination due to the presence of trace amounts of these solvents.

The various materials which may be employed as the latices and permeators in the timing layers of this invention are in general readily obtainable. An important feature of the present invention is the ability to preselect materials with varying characteristics, e.g., degrees of permeability, temperature dependence, etc., to tailor the timing layer for optimum performance in accordance with the particular photographic system employed and the specific sensitometric design of the selected system. As heretofore noted, the permeability or rate of diffusion at a given temperature may be controlled by such features as the latex particle size, the ratio of latex to permeator, etc.

Of significant advantage is the ability to control the rate of diffusion over a wide temperature latitude from hot to cold by preselection of a permeator having a specified temperature dependence. As heretofore described, the permeator so selected may possess inverse or normal temperature dependence. In the particular illustrative film unit previously described, best results were obtained with a permeator exhibiting normal temperature dependence.

To illustrate this point, substitution in the illustrative film unit of a graft polymer timing layer of the type disclosed in the aforementioned U. S. Pat. No. 3,575,701, e.g., a graft copolymer of acrylamide and diacetone acrylamide on a polyvinyl alcohol backbone in a molar ratio of l:3.2:l gave inferior pictures both in the hot and in the cold. This is believed to be due to the inverse temperature dependence of this layer. More specifically, lower dye densities were obtained in the cold due to the permeability of the timing layer being too rapid to in turn cause neutralization and subsequent dye immobilization too rapidly; whereas in the hot, some staining or discoloration was evidenced due to unwanted transfer of dye and/or other ingredients. In contrast with the graft timing layer (which also has the advantage of being coatable from aqueous media), the timing layer of the illustrative formulation employing a permeator having normal temperature dependence possessed a superior temperature curve, giving consistent high performance from temperatures ranging from hot to cold.

The exact reasons why timing layers possessing normal temperature dependence are superior in one system and those possessing inverse temperature dependence are superior in another system are at present not clearly defined. They may be due, at least in part, to such factors as whether or not the negative and positive components are retained together or separated following a predetermined development period, the particu-' lar imaging dyes employed, and other such features.

Apart from providing the permeation properties, the permeator employed serves as a coating aid. An aqueous emulsion of latex alone has been found to be a weak internal cohesion fluid. Just a small amount of a linear high polymer permeator such as polyacrylamide makes it readily coatable due to the viscoelastic properties of the permeator.

Apart from these many advantages, the timing layers of this invention may be employed at appreciably lower coverages than many of the prior timing layers without being too permeable. In other words, in general terms the materials heretofore used for this purpose had to be employed at greater coverages, i.e., thicker layers, in order to control properly the rate of permeability or diffusible of alkali to the neutralizing layer. The ability to employ thinner layers is of obvious advantage in those film units wherein exposure and/or viewing is to be made through the timing layer. The advantages of such thinner layers include such important factors as greater clarity, less light scatter or distortion, etc.

Since certain changes may be made in the above product and process without departing from the scope of the invention herein involved, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. In a photographic product including a neutralizing system for lowering the pH of an aqueous alkaline processing fluid, said neutralizing system including a neutralizing layer and a spacer layer so disposed with respect to the neutralizing layer that said processing fluid must first diffuse through the spacer layer before contacting said neutralizing layer;

the improvement wherein said spacer layer comprises as a continuous phase the coalesced essence of an aqueous film-forming synthetic polymer dispersion which is substantially impervious to said processing fluid and a discontinuous phase comprising a material which is permeable to said processing fluid.

2. A product as defined in claim 1 wherein said permeable material possesses a normal temperature dependence whereby its permeability to alkali is greater at higher temperatures an d less at lower temperatures.

3. A product as defined iri elai m 1 wherein said he? tralizing layer and said spacer layer are contained on a transparent support, said neutralizing layer being disposed between said spacer layer and said support.

4. A product as defined in claim 1 including a dyeable stratum.

5. A product as defined in claim 4 wherein said spacer layer is disposed between said dyeable stratum and said neutralizing layer.

6. A product as defined in claim 4 including at least one light-sensitive silver halide layer having a dye image-providing material associated therewith.

7. A product as defined in claim 6 wherein said spacer layer is disposed between said dyeable stratum and said neutralizing layer and said light-sensitive silver halide layer and associated dye image-providing material is disposed on the side of said dyeable stratum opposed from said spacer and neutralizing layers.

8. In an integral negative-positive film unit including a negative component comprising at least one lightsensitive silver halide layer having a dye imageproviding material associated therewith and a positive component including at least a dyeable stratum, said film unit being adapted to provide, upon exposure and subsequent development of the thus exposed film unit by applying an aqueous alkaline processing fluid, a color transfer image viewable without separation of said components as a reflection print, said film unit further including a neutralizing layer for lowering the environmental pH subsequent to application of said alkaline processing fluid and a spacer layer so disposed with respect to said neutralizing layer that said processing fluid must first diffuse through said spacer layer before contacting said neutralizing layer;

the improvement wherein said spacer layer comprises as a continuous phase the coalesced essence of an aqueous film-forming synthetic polymer dispersion which is substantially impermeable to said processing fluid and a discontinuous phase comprising a material which is permeable to said processing fluid.

9. A film unit as defined in claim 8 wherein said permeable material possesses a normal temperature dependence whereby its permeability to alkali is greater at higher temperatures and less at lower temperatures.

10. A film unit as defined in claim 9 wherein said permeable material comprises polyacrylamide.

11. A film unit as defined in claim 9 wherein the latex employed to prepare saidcoalesced essence possesses a particle size from about 0.095 p. to about 0.130 u.

12. A film unit as defined in claim 9 wherein the ratio of said coalesced essence to said permeable material in said spacer layer is from about 19:1 to about 99:1.

13. A film unit as defined in claim 8 wherein said negative component includes a red-sensitive silver halide emulsion having a cyan dye image-providing material associated therewith, a green-sensitive silver halide emulsion having a magenta dye image-providing material associated therewith and a blue-sensitive silver halide emulsion having a yellow dye image-providing material associated therewith.

14. A film unit as defined in claim 13 wherein said dye image-providing materials are initially soluble or diffusible in said aqueous alkaline processing fluid but are selectively rendered non-diffusible in an imagewise pattern as a function of development.

15. A film unit as defined in claim 8 wherein said negative and positive components are confined between a pair of support members at least the support member associated with said positive component being transparent.

16. A film unit as defined in claim 8 wherein said positive and negative components are confined on a transparent support member associated with said positive component.

17. A film unit as defined in claim 8 wherein said means for applying a reflecting layer comprises a layer of a white pigment disposed in a layer between said positive and negative components.

18. A film unit as defined in claim 8 wherein said means for applying a reflecting layer comprises a white pigment dispersed in said processing fluid.

19. A film unit as defined in claim 8 wherein said positive and negative components are laminated together.

20. A process for forming a color transfer image comprising the steps of exposing a film unit as defined in claim 8 to form a developable image and thereafter applying an aqueous alkaline processing fluid to develop said image and to form as a function of development an imagewise distribution of dye image-providing material which is transferred, at least in part, by diffusion, to said dyeable stratum to impart thereto a color transfer image viewable, without separation, by reflected light as a positive color reflection print.

21. A photosensitive element including a composite structure containing, as essential layers, in sequence, a

dimensionally stable alkaline solution impermeable opaque layer, a layer containing a cyan dye developer, a red-sensitive gelatino silver halide emulsion layer, a layer containing a magenta dye developer, a greensensitive gelatino silver halide emulsion layer, a layer containing a yellow dye developer, a blue-sensitive gelatino silver halide emulsion layer, a dyeable stratum, a spacer layer comprising as a continuous phase the coalesced essence of an aqueous film-forming synthetic polymer dispersion which is substantially impermeable to said processing fluid and a discontinuous phase comprising a material which is permeable to said processing fluid, a neutralizing layer comprising a polymeric acid in an amount sufficient to effect reduction of a processing fluid having a first pH at which said dye developers are soluble and diffusible to a second pH at which said dye developers are substantially insoluble and nondiffusible, a dimensionally stable alkaline solution impermeable transparent layer, and a rupturable container retaining an aqueous alkaline processing fluid having said first pH and containing dispersed therein a white inorganic pigment in a quantity sufficient to mask effectively said silver halide layers and any dye developer associated therewith after development and to provide a background for viewing a diffusion transfer image formed by development of said film unit, by reflected light, through said transparent layers, said rupturable container being fixedly positioned and extending transverse a leading edge of said photosensitive element so as to be capable of unidirectional discharge of the containers contents between said dyeable stratum and said blue-sensitive emulsion layer upon application of compressive force to said container.

22. A photosensitive element as defined in claim 21 wherein said permeable material comprises polyacrylamide and the ratio of said coalesced essence to polyaerylamide being from about 19:] to about 99:].

23. A photosensitive element as defined in claim 22 wherein the latex employed to prepare said coalesced essence has a particle size from about 0.095 p. to about 0.130 11..

24. A photosensitive element as defined in claim 23 wherein said coalesced essence is present in an amount such that, if said spacer layer consisted only of said coalesced essence, it would be impermeable to said alkaline processing fluid.

25. A photosensitive element as defined in claim 24 wherein said spacer layer contains about 300 to about 1,700 mgs. of solids per square foot of surface area.

26. A process for forming a visible image in color comprising the steps of exposing a light-sensitive silver halide layer having a dye image-providing material associated therewith to form a developable image; contacting said exposed layer with an aqueous alkaline processing composition to develop said image and to form, as a function of development, an imagewise distribution of said dye image-providing material which is diffusible in said processing composition; and transferring said imagewise distribution ofdiffusible dye imageproviding material by diffusion to a receiving element comprising a support having thereon, in order, a neutralizing layer; a spacer layer comprising as a continuous phase the coalesced essence of an aqueous filmforming synthetic polymer dispersion which is substantially impervious to said processing composition and a discontinuous phase comprising a material which is permeable to said processing composition; and a dyeable stratum, to impart to said dyeable stratum a color transfer image. 

2. A product as defined in claim 1 wherein said permeable material possesses a normal temperature dependenCe whereby its permeability to alkali is greater at higher temperatures and less at lower temperatures.
 3. A product as defined in claim 1 wherein said neutralizing layer and said spacer layer are contained on a transparent support, said neutralizing layer being disposed between said spacer layer and said support.
 4. A product as defined in claim 1 including a dyeable stratum.
 5. A product as defined in claim 4 wherein said spacer layer is disposed between said dyeable stratum and said neutralizing layer.
 6. A product as defined in claim 4 including at least one light-sensitive silver halide layer having a dye image-providing material associated therewith.
 7. A product as defined in claim 6 wherein said spacer layer is disposed between said dyeable stratum and said neutralizing layer and said light-sensitive silver halide layer and associated dye image-providing material is disposed on the side of said dyeable stratum opposed from said spacer and neutralizing layers.
 8. In an integral negative-positive film unit including a negative component comprising at least one light-sensitive silver halide layer having a dye image-providing material associated therewith and a positive component including at least a dyeable stratum, said film unit being adapted to provide, upon exposure and subsequent development of the thus exposed film unit by applying an aqueous alkaline processing fluid, a color transfer image viewable without separation of said components as a reflection print, said film unit further including a neutralizing layer for lowering the environmental pH subsequent to application of said alkaline processing fluid and a spacer layer so disposed with respect to said neutralizing layer that said processing fluid must first diffuse through said spacer layer before contacting said neutralizing layer; the improvement wherein said spacer layer comprises as a continuous phase the coalesced essence of an aqueous film-forming synthetic polymer dispersion which is substantially impermeable to said processing fluid and a discontinuous phase comprising a material which is permeable to said processing fluid.
 9. A film unit as defined in claim 8 wherein said permeable material possesses a normal temperature dependence whereby its permeability to alkali is greater at higher temperatures and less at lower temperatures.
 10. A film unit as defined in claim 9 wherein said permeable material comprises polyacrylamide.
 11. A film unit as defined in claim 9 wherein the latex employed to prepare said coalesced essence possesses a particle size from about 0.095 Mu to about 0.130 Mu .
 12. A film unit as defined in claim 9 wherein the ratio of said coalesced essence to said permeable material in said spacer layer is from about 19:1 to about 99:1.
 13. A film unit as defined in claim 8 wherein said negative component includes a red-sensitive silver halide emulsion having a cyan dye image-providing material associated therewith, a green-sensitive silver halide emulsion having a magenta dye image-providing material associated therewith and a blue-sensitive silver halide emulsion having a yellow dye image-providing material associated therewith.
 14. A film unit as defined in claim 13 wherein said dye image-providing materials are initially soluble or diffusible in said aqueous alkaline processing fluid but are selectively rendered non-diffusible in an imagewise pattern as a function of development.
 15. A film unit as defined in claim 8 wherein said negative and positive components are confined between a pair of support members at least the support member associated with said positive component being transparent.
 16. A film unit as defined in claim 8 wherein said positive and negative components are confined on a transparent support member associated with said positive component.
 17. A film unit as defined in claim 8 wherein said means for applying a reflecting layer comprises a layer of a white pigment disposed in a layeR between said positive and negative components.
 18. A film unit as defined in claim 8 wherein said means for applying a reflecting layer comprises a white pigment dispersed in said processing fluid.
 19. A film unit as defined in claim 8 wherein said positive and negative components are laminated together.
 20. A process for forming a color transfer image comprising the steps of exposing a film unit as defined in claim 8 to form a developable image and thereafter applying an aqueous alkaline processing fluid to develop said image and to form as a function of development an imagewise distribution of dye image-providing material which is transferred, at least in part, by diffusion, to said dyeable stratum to impart thereto a color transfer image viewable, without separation, by reflected light as a positive color reflection print.
 21. A photosensitive element including a composite structure containing, as essential layers, in sequence, a dimensionally stable alkaline solution impermeable opaque layer, a layer containing a cyan dye developer, a red-sensitive gelatino silver halide emulsion layer, a layer containing a magenta dye developer, a green-sensitive gelatino silver halide emulsion layer, a layer containing a yellow dye developer, a blue-sensitive gelatino silver halide emulsion layer, a dyeable stratum, a spacer layer comprising as a continuous phase the coalesced essence of an aqueous film-forming synthetic polymer dispersion which is substantially impermeable to said processing fluid and a discontinuous phase comprising a material which is permeable to said processing fluid, a neutralizing layer comprising a polymeric acid in an amount sufficient to effect reduction of a processing fluid having a first pH at which said dye developers are soluble and diffusible to a second pH at which said dye developers are substantially insoluble and non-diffusible, a dimensionally stable alkaline solution impermeable transparent layer, and a rupturable container retaining an aqueous alkaline processing fluid having said first pH and containing dispersed therein a white inorganic pigment in a quantity sufficient to mask effectively said silver halide layers and any dye developer associated therewith after development and to provide a background for viewing a diffusion transfer image formed by development of said film unit, by reflected light, through said transparent layers, said rupturable container being fixedly positioned and extending transverse a leading edge of said photosensitive element so as to be capable of unidirectional discharge of the container''s contents between said dyeable stratum and said blue-sensitive emulsion layer upon application of compressive force to said container.
 22. A photosensitive element as defined in claim 21 wherein said permeable material comprises polyacrylamide and the ratio of said coalesced essence to polyacrylamide being from about 19:1 to about 99:1.
 23. A photosensitive element as defined in claim 22 wherein the latex employed to prepare said coalesced essence has a particle size from about 0.095 Mu to about 0.130 Mu .
 24. A photosensitive element as defined in claim 23 wherein said coalesced essence is present in an amount such that, if said spacer layer consisted only of said coalesced essence, it would be impermeable to said alkaline processing fluid.
 25. A photosensitive element as defined in claim 24 wherein said spacer layer contains about 300 to about 1,700 mgs. of solids per square foot of surface area.
 26. A process for forming a visible image in color comprising the steps of exposing a light-sensitive silver halide layer having a dye image-providing material associated therewith to form a developable image; contacting said exposed layer with an aqueous alkaline processing composition to develop said image and to form, as a function of development, an imagewise distribution of said dye image-providing material which is diffusible in said processing composition; and traNsferring said imagewise distribution of diffusible dye image-providing material by diffusion to a receiving element comprising a support having thereon, in order, a neutralizing layer; a spacer layer comprising as a continuous phase the coalesced essence of an aqueous film-forming synthetic polymer dispersion which is substantially impervious to said processing composition and a discontinuous phase comprising a material which is permeable to said processing composition; and a dyeable stratum, to impart to said dyeable stratum a color transfer image. 